Hands-free kit for mobile radio-telephone handset

ABSTRACT

A hands-free kit for a mobile radio-telephone handset, the hands-free kit having an earpiece and an infra-red transmitter with the transmitter being able to relay audio signals from the handset to the earpiece. The earpiece includes an infra-red receiver for receiving audio signals from the transmitter. By positioning the transmitter in the line of sight of the earpiece receiver, audio signals may be relayed from the handset to the earpiece with the reduced likelihood of the earpiece becoming dislodged as the user moves his head.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to a hands-free kit for a mobileradio-telephone handset.

2. Description of the Prior Art

Concerns have recently grown over the safety of mobile radio-telephoneshandsets, otherwise known as cellular phones, which have been found toemit high levels of microwave radiation.

To reduce the risks associated with such handsets, a number ofhands-free kits have been devised which connect an earpiece andmicrophone to a handset via wires, thereby allowing the handset to belocated a safe distance from the user's head.

However, it has been found that the earpieces of such kits are easilydislodged by tension on the connecting wires caused, for example, by thewires catching on the user's outer garments as he moves his head.

More importantly, it has recently been suggested that the connectingwires of such kits act as a conduit, channelling microwave radiationfrom the handset to the user's head.

SUMMARY OF THE INVENTION

We have now devised an arrangement which overcomes the limitations ofexisting hand-free kits for mobile radio-telephone handsets.

According to a first aspect of the present invention, there is provideda hands-tree kit for a mobile radio-telephone handset, the kitcomprising an earpiece and an infra-red transmitter, the transmitterbeing arranged to relay audio signals from the handset to the earpiece,the earpiece comprising an infra-red receiver for receiving audiosignals from the transmitter.

Thus, by positioning the transmitter in line of sight of the receiver,audio signals may be relayed from the handset to the earpiece with thereduced likelihood of the earpiece becoming dislodged as the user moveshis head.

The transmitter may communicate with the handset via a wired or wirelessconnection, such as a radio frequency connection provided by Bluetooth®or Bluetooth®-type communications devices.

The receiver may be located at the distal end of a portion of theearpiece which, in use, projects forwards from the user's ear.

Preferably the receiver comprises a plurality of photosensitive devicesarranged to receive infra-red signals from different respectivedirections including the direction of the transmitter.

Alternatively, the earpiece may comprise means, provided on a forwardsprojecting portion of the earpiece, for reflecting audio signals from atleast the direction of the transmitter towards the receiver.

The transmitter is preferably arranged to be carried in the user'sbreast pocket or worn on the user's front, in line-of-sight of theearpiece receiver or of the reflecting means, and may be provided withmeans for attaching to an outer-garment worn by the user. For example,the attaching means may comprise a clip or pin for attaching thetransmitter to the breast pocket or the lapel of a jacket or to aneck-tie.

Alternatively the transmitter may be permanently mounted to, or providedwith means for temporarily attaching to, a part of a vehicle, forexample the vehicle dashboard or a seatbelt, in line-of-sight of theearpiece receiver.

Preferably, the hands-free kit also comprises a microphone forconnecting to the handset, the microphone preferably comprising part ofan integrated unit also comprising the transmitter.

Where the transmitter communicates with the handset via a wirelessconnection, the microphone preferably also communicates with the handsetvia the same wireless connection.

The transmitter may be powered from the power supply of the handset ormay comprise its own re-chargeable porter supply.

The earpiece preferably comprises a re-chargeable power supply, whichmay be arranged to be re-charged via a mains adapter or by plugging theearpiece, either directly or via an adaptor, into the cigarette lightersocket of a vehicle.

Most preferably the kit comprises a holder for the earpiece and thetransmitter via which respective re-chargeable power supplies of the twodevices may be charged.

The holder may be arranged to charge the earpiece and transmitter eitherdirectly from an external supply or via its own re-chargeable supply, toenable the earpiece and transmitter to be charged in the absence of saidexternal supply.

Typically, from a full state of charge, the power supply of thetransmitter will be exhausted sooner than that of the earpiece. Toensure that the transmitter is charged for at least as long as theearpiece, the holder is preferably arranged prevent the earpiece frombeing charged independently of the transmitter. For example, anelectrically conductive part of the transmitter may be arranged tobridge a pair of contacts of the holder to complete a charging circuitfor the earpiece. Thus, both the transmitter and the earpiece must befitted to the holder before the latter can be charged.

The holder may also or otherwise be arranged to prevent the transmitterfrom being charged independently of the earpiece.

The holder may be provided with means for visibly indicating its stateof charge and/or the state of charge of the transmitter and/or of theearpiece. However, the transmitter and the earpiece preferably compriseindependent means for visibly indicating their respective states ofcharge, the holder preferably comprising a lidded case having a portionwhich is at least partially transparent and through which the chargeindicating means of the transmitter and earpiece may be viewed.

In either case, the indicating means preferably comprise respectivelights, e.g. light emitting diodes, which may, for example, beconstantly illuminated, extinguished or illuminated intermittently toindicate different states of charge.

Most preferably the transmitter and earpiece each comprise a respectivelight which is illuminated intermittently when the device is operating(to indicate that the device is charged), is constantly illuminated whenthe device is being charged and is extinguished when the device hasexhausted its power supply.

Preferably the earpiece emits an audible warning signal to indicate whenthe power supply of the transmitter and/or the earpiece is nearingexhaustion. Preferably the earpiece emits a periodic audible signal,with the frequency of the emitted signal increasing as the power supplyof the earpiece and/or the transmitter is exhausted. For example, theearpiece may emit an audible signal every 5 minutes when there isbetween 5 and 30 minutes of charge remaining in the transmitter and/orthe receiver, every 1 minute when between 30 seconds and 5 minutes ofcharge remains and every second when less that 1 second of chargeremains.

Signals transmitted from the transmitter to the receiver may beencrypted.

The transmitter and receiver may be arranged to respectively encode anddecode signals using a unique encryption algorithm.

Alternatively, the transmitter and receiver may be arranged torespectively encode and decode signals using one of a plurality ofencryption algorithms chosen on a random basis, the number of possibleencryption algorithms being sufficient to ensure an acceptably lowlikelihood of the same encryption algorithm being used by twotransmitter/receiver pairs in the same vicinity.

In either case, the transmitter and receiver may be pre-programmed withan appropriate encryption key. However, the encryption key is preferablytransmitted from the transmitter to the receiver, having preferably beengenerated by the transmitter.

Where the encryption key is generated by the transmitter, the encryptionalgorithm may, for example, be derived from the phone number or otheridentification code of the handset with which the hands-free kit is tobe used, or a new key, chosen at random, may be transmitted to thereceiver on a periodic basis, for example each time the transmitter ischarged.

The transmitter may also or otherwise be arranged to transmit anidentification signal to identify itself to the earpiece.

The identification signal may be unique or may be chosen at random fromone of a plurality of possible signals, the number of possible signalsbeing sufficient to ensure an acceptably low likelihood of the sameidentification signal being used by two transmitter/receiver pairs inthe same vicinity.

In either case, the transmitter and receiver may be pre-programmed tooperate using a particular identification signal. However, theidentification signal to be used is preferably communicated from thetransmitter to the receiver, having preferably been generated internallyby the transmitter.

Where the identification signal to be used is generated by thetransmitter, the signal may, for example, be derived from the phonenumber or other identification code of the handset with which thehands-free kit is to be used, or a new signal, chosen at random, may becommunicated to the earpiece on a periodic basis, for example each timethe transmitter is charged.

The earpiece may be arranged to respond to an invalid identificationsignal by emitting an audible warning signal.

The transmitter is preferably arranged to periodically transmit saididentification signal.

The earpiece may be arranged to provide an audible alarm signal it avalid identification signal is not received over a pre-determined periodof time.

Most preferably, the earpiece is arranged to operate for periods in astandby mode, wherein one or more functions of the earpiece are disabledto conserve power, the earpiece preferably being arranged to enter thestandby mode in the absence of a received signal or if a valididentification signal is not received. The or each disabled function ispreferably restored in response to a received signal, preferably only ifthat signal comprises a valid identification signal.

Entry into the standby mode may be immediate or may be delayed in one ormore of the above circumstances.

For example, the earpiece may be arranged to enter a standby mode in theabsence of a received signal or if a valid identification signal (suchas one transmitted periodically by the transmitter) is not received overa pre-determined period of time. Preferably, the earpiece will thenreturn to full functionality only on receiving a valid identificationsignal.

The transmitter is preferably arranged to operate for periods in astandby mode, wherein one or more functions of the transmitter aredisabled to conserve power, in the absence of an audio signal from thehandset.

We have found that, in use, the amount of infra-red light received bythe earpiece receiver from the transmitter varies as a user moves hishead. We have also found that a high level of ambient light can corruptthe infra-red signals received by the earpiece.

To counteract these effects, the hands-free kit may be arranged totransmit infra-red light of a constantly high level of intensity, suchthat the receiver is certain to receive the infra-red light emitted bythe transmitter over a range of orientations of the user's head and overa range of ambient light levels.

However, such an arrangement in clearly wasteful of the limited amountof power available to the transmitter as, except in a few extremeconditions, only a low intensity of infra-red light need be emitted bythe transmitter.

To reduce the level of power consumption of the transmitter, whilstensuring that an adequate signal is always received by the earpiecereceiver, the hands-free kit therefore preferably comprises a secondinfra-red receiver, located adjacent the transmitter, and means forvarying the intensity of the infra-red light emitted by the transmitteraccording the amount of infra-red light received by the second receiver.

The earpiece preferably comprises means for reflecting a portion of theinfra-red light emitted by the transmitter back towards the secondreceiver.

The reflecting means preferably comprise a part-spherical, multi-facetedarrangement of mirrors, which is preferably located at the distal end ofthe forward projecting portion of the earpiece. Each facet preferablycomprises a respective concave parabolic mirror.

An alternative means for optimising the amount of light received by theearpiece from the transmitter in accordance with the present invention,is to provide a set-up mode, wherein the transmitter emits a lightsignal of substantially constant amplitude and the earpiece emits aperiodic audible signal, whose periodicity varies in accordance with theamount of light received from the transmitter as the position of thetransmitter is adjusted by a user, for example by increasing infrequency with the amount of light received from the transmitter.

According to a second aspect of the present invention, there is provideda mobile radio-telephone arrangement comprising an earpiece and a mobileradio-telephone handset comprising an infra-red transmitter for relayingaudio signals from the handset to the earpiece, the earpiece comprisingan infra-red receiver for receiving audio signals from the transmitter.

According to a third aspect of the present invention, there is provideda mobile radio-telephone arrangement comprising a mobile radio-telephonehandset and a hands-free kit comprising an infrared transmitter locatedat the breast of a user for relaying incoming audio signals from thehandset to an earpiece worn by the user, the earpiece comprising aninfra-red receiver for receiving audio signals from the transmitter

According to a fourth aspect of the present invention, there is providedan earpiece for attaching to an ear of a user and comprising aninfra-red receiver.

Preferably the receiver is arranged to receive signals from an infra-redtransmitter positioned at the breast of a person wearing the earpiece.

A preferred embodiment of earpiece comprises a tail portion for hookingaround the ear of the wearer, a portion which extends over and forwardsfrom the user's ear and a portion which extends rearwards from the frontof the device to position a microphone over the external auditory canalof the wearer.

Preferably an elastomeric grip is fitted to the tail portion of theearpiece, which is preferably replaceable to allow the shape of thedevice to be readily modified to fit different sized and shaped ears andthe device to be personalised to the wearer's taste by replacing thegrip with one of a different colour.

Preferably the front of the earpiece is provided with a window, behindwhich a pair of photosensitive devices are arranged to receive infra-redsignals from different respective directions.

Preferably the tail portion of the earpiece houses electronic circuitryand a rechargeable power supply.

Preferably the microphone is rotatable about the axis of the rearwardlyprojecting portion, to enable the earpiece to be configured for fittingto either the left or the right ear of the wearer.

Preferably abutting parts of the rearwardly projecting portion and ahousing of the microphone ensure that the microphone can only be rotatedthrough 180 degrees between its left and right handed orientations.

According to a fifth aspect of the present invention, there is providedan audio apparatus comprising a headset, an infra-red transmitter fortransmitting audio signals to the headset, an infra-red receiver locatedadjacent the transmitter and means for varying the intensity of theinfra-red light emitted by the transmitter according to the amount ofinfra-red light received by the receiver.

Preferably the headset comprises means for reflecting a portion of theinfra-red light emitted by the transmitter towards the receiver.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present invention will now be described by way ofexamples only and with reference to the accompanying drawings, in which:

FIGS. 1 to 3 are respectively a front view, a side view and a rear viewof a person wearing an apparatus in accordance with the presentinvention;

FIGS. 4 to 6 are respectively a front view, and perspective views fromeach side of a first embodiment of earpiece in accordance with thepresent invention;

FIG. 7 is a front view showing the earpiece of FIGS. 4 to 6 opened forfitting to a person's ear;

FIG. 8 is a side perspective view showing the earpiece of FIGS. 4 to 6fitted to a person's ear;

FIG. 9 is a side view of a second embodiment of earpiece in accordancewith the present invention;

FIGS. 10 to 13 are respectively views from opposite sides and twoperspective views of a third embodiment of earpiece in accordance withthe present invention;

FIGS. 14 to 16 are respectively a front and rear views and a perspectiveview of an embodiment of transmitter unit in accordance with the presentinvention; and

FIGS. 17 to 21 are respectively three perspective views, a view of theunderside and a front view of an embodiment of holder in accordance withthe present invention.

DETAILED DESCRIPTION OF THE DRAWING FIGURE AND PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 3 of the drawings, a person 2 is shown wearing ahands-free kit in accordance with the present invention.

The hands-free kit comprises an earpiece 4 and a transmitter unit 6,clipped to the breast pocket 8 of the person's jacket, for relayingaudio signals from a mobile radio telephone-handset (not shown), via aninfra-red transmitter of the unit, to an infra-red receiver 10 of theearpiece 4.

The transmitter unit 6 also comprises a microphone, with audio signalsbeing transmitted from the handset to the infra-red transmitter of theunit and from the microphone to the handset, via either a wired or awireless link, so that the handset may be located a safe distance fromthe user's head.

The earpiece 4 is arranged to become activated upon receiving an audiosignal from the transmitter unit 6, it preceded by a valididentification code, to provide an audible output of the audio signalvia a speaker 14 adjacent the user's ear 12.

The transmitter unit 6 is arranged to periodically retransmit theidentity code within an audio stream, the earpiece 4 being arrangedentering a standby mode, to conserve power, in the absence of a receivedsignal or where a valid identity code is not received within a period oftime.

The transmitter unit 6 is also arranged to enter a standby mode, toconserve power, in the absence of a signal from the handset.

The transmitter unit 6 and earpiece 4 are powered by respectiverechargeable supplies and are re-charged by fitting the two parts to aholder, such as that described in detail below. As the power supply ofthe earpiece 4 and/or the transmitter unit 6 is nearing exhaustion, theearpiece 4 periodically emits an audible warning signal whose frequencyincreases, the nearer the power supply of either unit comes to beingfully discharged.

Each time the transmitter unit 6 and earpiece 4 are fitted to the holderfor charging, a new identification code is generated at random by thetransmitter unit 6 and communicated to the earpiece 4, by which theearpiece 4 can then identify audio signals originating from thattransmitter 6.

The earpiece 4 is also arranged, for example by pre-programming theearpiece or by programming the earpiece in-situ, to generate an audibleoutput of received audio signals preceded by at least one otheridentification code, such as may be assigned to an infra-red transmitterinstalled in a public facility or retail outlet, the earpiece 4preferably being arranged to give precedence to signals identified ashaving been received from the transmitter unit 6.

To facilitate the reception of audio signals from sources other than thetransmitter unit 6, the infra-red receiver 10 of the earpiece 4comprises a pair of photosensitive devices, one of which is directeddownwards towards the transmitter unit 6, the other being directedupwards to receive signals from said other sources.

The transmitter unit 6 is also provided with an infrared receiver (notshown), adjacent the infra-red transmitter thereof, for adjusting thelevel of intensity of infra-red signals emitted from the unit, accordingto ambient light levels.

A first embodiment of earpiece 4 is shown in detail in FIGS. 4 to 6. Twopart-cylindrical halves 16, 18 of a clip 20 are hingedly joined togetheralong the top of the earpiece and are each lined with a cushioningmaterial 22. A telescopic rod 24 extends forwards from the clip 20 andis provided at its distal end with an infra-red receiver 26. A portionof the rod, also at its distal end, is touch-sensitive for activatingand de-activating the electronic circuitry of the earpiece. In itsretracted position, the projecting portion of the rod 24 is arranged tofit either directly, or via an adaptor, into the cigarette lightersocket of a vehicle to recharge the power supply of the earpiece viaelectrical contacts on the exterior of the rod.

The distal end of the rod 24 may also be provided with a part-sphericalmirrored portion (not shown), preferably comprising a plurality ofconcave parabolic facets, for reflecting a portion of the intra-redlight emitted by the transmitter back towards an infra-red receiverlocated adjacent the transmitter.

Means are provided for varying the intensity of light emitted by thetransmitter 6 according to the amount of light reflected to ensure thatthe amount of infra-red light falling upon the receiver 26 of theearpiece 4 remains substantially constant regardless of the orientationof the person, a head and thus the distance and/or misalignment betweenthe transmitter 6 and the earpiece receiver 26.

The infra-red receiver located adjacent the transmitter 6 may also orotherwise be used to adjust the intensity of light emitted by thetransmitter according to ambient light levels.

A speaker 14 and a housing 28 depend on opposite sides of the earpiece,from respective halves 16, 18 of the clip 20, the housing 28accommodating the re-chargeable power supply and electronic circuitry ofthe earpiece 4.

The earpiece 4 is fitted to a person's ear 12 as shown in FIGS. 7 and 8by first separating the speaker 14 and housing 28 parts of the earpieceto open the clip 20 and then bringing the two parts 14, 28 backtogether, on opposite sides of the person's ear 12 such that the clip 20becomes attached to the top of the ear 12, with the speaker 14positioned within the ear, the housing 28 extending behind the ear andthe telescopic rod 24 extending forwards from the ear.

A second embodiment of earpiece 4 is shown in FIG. 9, and comprises aparabolic concave mirror 30 for reflecting signals from the transmitterto a receiver located adjacent the speaker 14.

A third embodiment of earpiece 4 is shown in FIGS. 10 to 12 and, in analternative configuration in FIG. 13, the earpiece comprising a tailportion 32 for hooking around the ear of the wearer, a portion 34 which,in use, extends forwards from the wearer's ear and a portion 36 whichextends rearwards from the front of the device to support a microphone38 over the external auditory canal of the wearer.

An elastomeric grip 40, fitted to the tail portion 32 of the earpiece isreplaceable to allow the shape of the device to be readily modified tofit different sized and shaped ears and the device to be personalised tothe wearer's taste by replacing the grip 40 with one of a differentcolour.

The front of the earpiece is provided with a window 42, behind which apair of photosensitive devices are arranged to receive infra-red signalsfrom above and below the earpiece respectively.

The tail portion 32 of the earpiece houses electronic circuitry and arechargeable power supply.

The microphone 38 is rotatable about the axis of the rearwardlyprojecting portion 36, as illustrated in FIG. 13, to enable the earpieceto be configured for fitting either to the left or the right ear of thewearer.

Abutting parts of the portion 36 and a housing 44 of the microphoneensure that the microphone can only be rotated through 180 degreesbetween its left and right handed orientations.

A preferred transmitter unit 6 is shown in FIGS. 14 to 16 and comprisesa main body 46, within which electronic circuitry and a re-chargeablepower supply are housed, the body part 46 being provided at oppositeends with an infra-red emitter 48 and a lead 50 for connecting thetransmitter to a mobile radiotelephone handset.

A clip 52 having an integral metallic fastening pin 53 is provided atthe rear of the body part 46, for respectively clipping or pinning thetransmitter unit to an outer garment of user, the clip 52 beingdetachable from the body part to be replaced by an alternative fasteningdevice if required.

FIGS. 17 to 21 show a holder in the form of a case 54, having aninternal tray 56 shaped to receive the earpiece and transmitter units ofFIGS. 10 to 16, as shown in FIG. 19, for charging those devices eitherdirectly from an external power supply or via a rechargeable powersource of the case.

The case 54 is provided with a socket 58 for connecting to said externalpower supply and two pairs of charging pins 60, 62 arranged to registerwith respective pairs of terminals 64, 68 formed in the bodies of theearpiece and transmitter units. A further pair of electrical contacts70, 72 are arranged to be bridged by the fastening pin 53 of thetransmitter unit 6, when that unit is fitted to the case, to complete acircuit for charging the earpiece 4.

The lid 74 of the case 54 is partially transparent, to provide a view ofrespective light emitting diodes (not shown) of the earpiece andtransmitter units, which are illuminated whilst the devices are beingcharged. The same lights are preferably illuminated intermittentlywhilst the devices are operating (to provide an indication of whetherthe devices are charged), and are extinguished when their respectivepower supplies are exhausted.

An aperture 76 in the side of the case 54 provides a passageway throughwhich the connecting lead 50 of the transmitter unit 6 may exit thecase, to then be routed around a channel 78 formed in the sides of thecase and secured in place by locating a connector at the end of the leadwithin a correspondingly shaped recess 80 formed in the base of thecase.

The wireless, hands-free arrangements thus described provide a muchsafer and more convenient alternative to existing hand-free arrangementsfor use with mobile radio-telephone handsets.

1. A hands-free kit for a mobile radio-telephone handset, saidhands-free kit comprising: an earpiece for a user, said earpiece havingan infra-red receiver; a transmitter comprising means for directlyrelaying audio signals from the mobile radio-telephone handset to saidearpiece when said earpiece is worn by the user, said infra-red receiverof said earpiece receiving said audio signals from said transmitter whensaid transmitter is also being worn or carried by, or attached to, theuser; and, means for attaching, carrying or wearing said transmitter bythe user on a front side of the user's body and in a line of sight ofsaid earpiece for direct transmission from said transmitter worn orcarried by, or attached to, the user to said infra-red receiver of saidearpiece, or for direct transmission from said transmitter to a forwardsprojecting portion of said earpiece having means for reflecting audiosignals from, at least, a direction of said transmitter towards saidinfra-red receiver, wherein the means for reflecting audio signalsincludes a parabolic concave mirror, said hands-free kit for themobile-telephone handset being operable when said earpiece, saidtransmitter and said means for attaching, carrying or wearing saidtransmitter are all located exclusively on the user's body.
 2. Thehands-free kit for a mobile radio-telephone handset according to claim1, wherein said infra-red receiver comprises a plurality ofphotosensitive devices for receiving infra-red signals from differentdirections, including a direction leading from said transmitter.
 3. Thehands-free kit for a mobile radio-telephone handset according to claim1, wherein said transmitter communicates with the mobile-radio-telephonehandset via a wireless connection.
 4. The hands-free kit for a mobileradio-telephone handset according to claim 1, wherein said receiver islocated at a distal end of a portion of said earpiece with said receiverprojecting forward from an ear of the user.
 5. The hands-free kit for amobile radio-telephone handset according to claim 1, further comprisinga microphone and means for connecting said microphone to the mobileradio-telephone handset.
 6. The hands-free kit for a mobileradio-telephone handset according to claim 5, wherein said microphonecomprises a part of an integrated unit also comprising a transmitter. 7.The hands-free kit for a mobile radio-telephone handset according toclaim 5, wherein said transmitter communicates with the mobileradio-telephone handset via a wireless connection, and said microphoneand said transmitter each communicate with the mobile radio-telephonehandset via the same said wireless connection.
 8. The hands-free kit fora mobile radio-telephone handset according to claim 1, wherein saidtransmitter comprises a rechargeable power Supply.
 9. The hands-free kitfor a mobile radio-telephone handset according to claim 1, wherein saidearpiece comprises a rechargeable power supply.
 10. The hands-free kitfor a mobile radio-telephone handset according to claim 1, wherein saidtransmitter and said earpiece each have a rechargeable power supply. 11.The hands-free kit for a mobile radio-telephone handset according toclaim 10, further comprising a holder for said earpiece and saidtransmitter by which said rechargeable power supply for each of saidearpiece and said transmitter are able to be charged.
 12. The hands-freekit for a mobile radio-telephone handset according to claim 11, whereinsaid holder comprises means for charging said earpiece and saidtransmitter directly from an external power supply.
 13. The hands-freekit for a mobile radio-telephone handset according to claim 11, whereinsaid holder comprises a rechargeable power supply and means for chargingsaid earpiece and said transmitter via said rechargeable power supply ofsaid holder.
 14. The hands-free kit for a mobile radio-telephone handsetaccording to claim 11, wherein said holder includes means for preventingsaid earpiece from being charged independently of said transmitter. 15.The hands-free kit for a mobile radio-telephone handset according toclaim 11, wherein said holder includes means for preventing saidearpiece from being charged independently of said earpiece.
 16. Thehands-free kit for a mobile radio-telephone handset according to claim11, wherein said holder includes means for visibly indicating a state ofcharge for said holder.
 17. The hands-free kit for a mobileradio-telephone handset according to claim 11, wherein said holderincludes means for visibly indicating a state of charge for at least oneof said transmitter and said earpiece.
 18. The hands-free kit for amobile radio-telephone handset according to claim 17, wherein said meansfor visibly indicating a state of charge includes a light.
 19. Thehands-free kit for a mobile radio-telephone handset according to claim18, wherein said light is constantly illuminated, extinguished orilluminated intermittently for indicating different states of charge.20. The hands-free kit for a mobile radio-telephone handset according toclaim 8, wherein said transmitter includes means for visibly indicatinga state of charge.
 21. The hands-free kit for a mobile radio-telephonehandset according to claim 20, wherein said means for visibly indicatinga state of charge includes a light.
 22. The hands-free kit for a mobileradio-telephone handset according to claim 21, wherein said light isconstantly illuminated, extinguished or illuminated intermittently forindicating different states of charge.
 23. The hands-free kit for amobile radio-telephone handset according to claim 20, further comprisinga holder for said transmitter by which said rechargeable power supplyfor said transmitter is able to be charged, said holder comprising alidded case having a portion of which is at least partially transparentand through which said means for visibly indicating a state of chargefor said transmitter is able to be viewed.
 24. The hands-free kit for amobile radio-telephone handset according to claim 9, wherein saidearpiece includes means for visibly indicating a state of charge. 25.The hands-free kit for a mobile radio-telephone handset according toclaim 24, wherein said means for visibly indicating a state of chargeincludes a light.
 26. The hands-free kit for a mobile radio-telephonehandset according to claim 25, wherein said light is constantlyilluminated, extinguished or illuminated intermittently for indicatingdifferent states of charge.
 27. The hands-free kit for a mobileradio-telephone handset according to claim 24, further comprising aholder for said earpiece by which said rechargeable power supply forsaid earpiece is able to be charged, said holder comprising a liddedcase having a portion of which is at least partially transparent andthrough which said means for visibly indicating a state of charge forsaid earpiece is able to be viewed.
 28. The hands-free kit for a mobileradio-telephone handset according to claim 9, wherein said earpieceemits an audible warning signal for indicating where a power supply ofat least one of said transmitter and said earpiece is nearingexhaustion.
 29. The hands-free kit for a mobile radio-telephone handsetaccording to claim 28, wherein said audible warning signal comprises aperiodic signal that increases in frequency as said power supply of atleast one of said earpiece and said transmitter is exhausted.
 30. Thehands-free kit for a mobile radio-telephone handset according to claim1, wherein said audio signals transmitted from said transmitter to saidinfix-red receiver are encrypted.
 31. The hands-free kit for a mobileradio-telephone handset according to claim 1, wherein said transmittertransmits an identification signal for identifying said transmitter tosaid earpiece.
 32. The hands-free kit for a mobile radio-telephonehandset according to claim 31, wherein said identification signal is aunique signal.
 33. The hands-free kit for a mobile radio-telephonehandset according to claim 31, wherein said identification signal ischosen on a random basis from one of a plurality of possibleidentification signals.
 34. The hands-free kit for a mobileradio-telephone handset according to claim 31, wherein said transmitterand said infra-red receiver are pre-programmed for operating aparticular said identification signal.
 35. The hands-free kit for amobile radio-telephone handset according to claim 31, wherein saididentification signal is communicated from said transmitter to saidinfra-red receiver.
 36. The hands-he kit for a mobile radio-telephonehandset according to claim 35, wherein said identification signal isgenerated by said transmitter.
 37. The hands-free kit for a mobileradio-telephone handset according to claim 36, wherein saididentification signal is derived from an identification code of themobile radio-telephone handset with which said hands-free kit is to beused.
 38. The hands-free kit for a mobile radio-telephone handsetaccording to claim 37, wherein said identification code is a telephonenumber.
 39. The hands-free kit for a mobile radio-telephone handsetaccording to claim 36, wherein said identification signal is chosen on arandom basis.
 40. The hands-free kit for a mobile radio-telephonehandset according to claim 39, wherein a new identification signal,chosen on a random basis, is communicated to said earpiece on a periodicbasis.
 41. The hands-free kit for a mobile radio-telephone handsetaccording to claim 31, wherein said earpiece responds to an invalid saididentification signal by emitting an audible warning signal.
 42. Thehands-free kit for a mobile radio-telephone handset according to claim31, wherein said transmitter periodically transmits said identificationsignal within a stream of said audio signals.
 43. The hands-free kit fora mobile radio-telephone handset according to claim 42, wherein saidearpiece provides an audible alarm signal if a valid said identificationsignal is not received within a predetermined period of time.
 44. Thehands-free kit for a mobile radio-telephone handset according to claim1, wherein said earpiece operates for periods in a standby mode with atleast one function of said earpiece is disabled for conservingelectrical power.
 45. The hands-free kit for a mobile radio-telephonehandset according to claim 44, wherein said earpiece enters said standbymode when a received audio signal is absent.
 46. The hands-free kit fora mobile radio-telephone handset according to claim 44, wherein saidtransmitter transmits an identification signal for identifying saidtransmitter to said earpiece with said earpiece entering said standby ifa valid said identification signal is not received.
 47. The hands-freekit for a mobile radio-telephone handset according to claim 44, whereinsaid at least one function having been disabled is restored in responseto a received audio signal.
 48. The hands-free kit for a mobileradio-telephone handset according to claim 47, wherein said at least onefunction having been disabled is only restored if said received audiosignal comprises a valid said identification signal.
 49. The hands-freekit for a mobile radio-telephone handset according to claim 44, whereinentry into said standby mode is immediate.
 50. The hands-free kit for amobile radio-telephone handset according to claim 44, wherein entry intosaid standby mode is delayed.
 51. The hands-free kit for a mobileradio-telephone handset according to claim 1, wherein said transmitteroperates for periods in a standby mode with at least one function ofsaid transmitter being disabled for conserving electrical power in anabsence of said audio signals from the mobile radio-telephone handset.52. The hands-free kit for a mobile radio-telephone handset according toclaim 1, further comprising: an additional infra-red receiver positionedadjacent said transmitter; and, means for varying intensity of infra-redlight emitted by said transmitter according to an amount of infra-redlight received by said additional infra-red receiver.
 53. The hands-freekit for a mobile radio-telephone handset according to claim 1, whereinsaid hands-free kit includes a set-up mode in which said transmitteremits a light signal of substantially constant amplitude and saidearpiece emits a periodic audible signal having a periodicity varyingaccording to an amount of light received from said transmitter aspositioning of said transmitter is adjusted by a user.
 54. Thehands-free kit for a mobile radio-telephone handset according to claim1, wherein said means for attaching, carrying or wearing saidtransmitter by the user in a line of sight of said earpiece is capableof being worn by the user at the user's breast.
 55. A method for using ahands-free kit for a mobile radiotelephone handset, said hands-free kitcomprising: an earpiece for a user, said earpiece having an infra-redreceiver; a transmitter comprising means for relaying audio signals fromthe mobile radio-telephone handset to said earpiece, said infra-redreceiver of said earpiece receiving said audio signals; and, means forattaching, carrying or wearing said transmitter by the user on a frontside of the user's body and in a line of sight of said earpiece, saidmethod for comprising the steps of: wearing said earpiece by the user;carrying or wearing said transmitter by the user on the front side ofthe user's body and in said line of sight of said earpiece; directlytransmitting the audio signals from said transmitter, when saidtransmitter is worn or carried by, or attached to, the user, and in aline of sight of said infra-red receiver, to said infra-red receiver ofsaid earpiece worn by the user, or directly transmitting the audiosignals from said transmitter to a forwards projecting portion of saidearpiece having means for reflecting audio signals from, at least, adirection of said transmitter towards said infra-red receiver, whereinthe means for reflecting audio signals includes a parabolic concavemirror; and operating said hands-free kit for the mobile-telephonehandset by the user when said earpiece, said transmitter and said meansfor attaching, carrying or wearing said transmitter are all locatedexclusively on the user's body.
 56. The method for using a hands-freekit for a mobile radio-telephone handset according to claim 55, whereinsaid step of carrying or wearing said transmitter by the user in saidline of sight of said earpiece is carried out by the user wearing saidtransmitter at the user's breast.
 57. A hands-free kit for a mobileradio-telephone handset, said hands-free kit comprising: an earpiece fora user, said earpiece having an infra-red receiver; a transmittercomprising means for directly relaying audio signals from the mobileradio-telephone handset to said earpiece when said earpiece is worn bythe user, said transmitter further including means for encoding saidaudio signals using at least one encryption algorithm, said infra-redreceiver of said earpiece receiving said audio signals from saidtransmitter when said transmitter is also being worn or carried by, orattached to, the user, said infra-red receiver including means fordecoding said audio signals so encoded by said transmitter; and, meansfor attaching, carrying or wearing said transmitter by the user on afront side of the user's body and in a line of sight of said earpiecefor direct transmission from said transmitter worn or carried by, orattached to, the user to said earpiece, or for direct transmission to aforwards projecting portion of said earpiece, the forward, projectingportion having a parabolic concave mirror for reflecting audio signalsfrom, at least, a direction of said transmitter towards said infraredreceiver, said hands-free kit for the mobile-telephone handset beingoperable when said earpiece, said transmitter and said means forattaching, carrying or wearing said transmitter are all locatedexclusively on the user's body.
 58. The hands-free kit for a mobileradio-telephone handset according to claim 57, wherein said means forencoding said audio signals and means for decoding said audio signalsuse one of a plurality of encryption algorithms chosen on a randombasis.
 59. The hands-free kit for a mobile radio-telephone handsetaccording to claim 57, wherein said transmitter and said infra-redreceiver are pre-programmed with an encryption key.
 60. The hands-freekit for a mobile radio-telephone handset according to claim 59, whereinsaid encryption key is transmitted from said transmitter to saidinfra-red receiver.
 61. The hands-free kit for a mobile radio-telephonehandset according to claim 60, wherein said encryption key is generatedby said transmitter.
 62. The hands-free kit for a mobile radio-telephonehandset according to claim 61, wherein said encryption key is derivedfrom an identification code of said hands-free kit being used.
 63. Thehands-free kit for a mobile radio-telephone handset according to claim62, wherein said identification code is a telephone number.
 64. Thehands-free kit for a mobile radio-telephone handset according to claim62, wherein said encryption key is chosen on a random basis.
 65. Thehands-free kit for a mobile radio-telephone handset according to claim64, wherein a new encryption key, chosen on a random basis, istransmitted to said infra-red receiver on a periodic basis.